Drill bit



June 4, 1940. M. HoKANsoN DRILL BIT 'Filed Jan. 1S, 1959 4 sheets-sheet5 INVENTOR.

BY 840m ATTORNEY.

June 4, 1940. M. HoKANsoN DRILL BIT Filed Jan. 18, 1939 4 Sheets-Sheet 4ATTORNEY.

yPatented June 4, 1940 PATENT OFFICE DRILL BIT Martin Hokanson,

Eidco, Incorporated, Duluth,

tion' of Minnesotay Duluth, Minn., assgnor to Minn., a corpora-Application January 18, 1939,v Serial No. 251,630

9 Claims.

/ This invention relates to percussion drills, and' this application isa continuation-in-part of my copending application Ser. No. 145,726,iiled June 1, 1937.

The principal object or novelty of the invention is that the bit hasinherent exibility and which may be modified to suit the specific characteristics or quality of the material drilled in, and for which purposeit is preferably formed of a plurality of separable parts, resulting inthe following novel and advantageous features:

. Increased speed in drilling.

. Decreased gauge loss.

. Less work involved in resharpening.

. Greater number of resharpenings.

. More durable.

Less expensive to use, because any par-t that wears faster than anotherpart can replaced when worn at less cost than the cost of a regular bit.f

' '7. Perfect fect hole.

8. Reaming and cutting edges are separate and independent of eachotherand can be regulated independently of each other to suit the needof the particular drilling problem at` hand.

9. The length of the cutting edge can be regulated without affecting thegauge of the bit.

10. The cutting edge can be made to cut ahead of, in the same planewith, or follow theA reaming edge of the bit, by merely changing thelength, of the auxiliary portion of the bit.

Another object is to provide a novel method of sharpening the improvedbit. g

Other objects and advantages of the invention will appear in thefollowing description thereof.

Referring now to the accompanying drawings, forming part of thisapplication, and wherein like reference characters indicate like parts:

Figure lis a central vertical section of a bit head embodying theinvention.

Figure 2 is a similar view taken at reaming quality, thus drilling aperright angles l to Figure 1.

v-us

Figure 3 is a plan view of the cutting face of the bit illustrated inFigures 1 and 2.

Figure 4 is a central vertical section of a modi- 4klied form ofauxiliary portion of thebit, and is illustrative of a common cross-bit.

Figure 5 is a face view of Figure 4, illustrating howsuch an auxiliarycutting portionof the bit head may be made in separable sections.

Figure 6 is-a central vertical section of a modified form of separablebit.

Figure 'Z is a plan view of the cutting face of the bit shownin Figure6,

of its division.

(Cl. Z-64.)

Figure 8 is a plan view of the cutting face of a bit such as shownxinFigures 1, 2, and 3 but with the auxiliary portion .thereof made in twoseparable halves.

Figure 9 is an elevation of one of the divisions 5 of the auxiliaryportions as viewed on the plane a central vertical sectional viewinvention showing a Figure 10 is of a modified form of the plurality ofauxiliary bits. I

Figure 11 is a face view of the cutting edge of Figure 10.

Figure 12 is an elevation of one of the auxiliary members.

Figure 13 is a similar view at right angles to-l Figure 12.

Figure 14 is a plan view of the cutting face of the member shown inFigure12.

Figure 15 is a central vertical section of a still further modiiied formof bit, particularly in re- 20 -spect to that type illustrated in Figure6, and

showing a sharpening wheel as applied thereto. Figure 16 is a similarview of the bit taken at right angles to Figure 15.

Figure 17 is a plan View of the bit illustrated in Figures 15 and 16.

In Figures 1, 2 and 3, the body portion of the bit head is shown at l,it being hollow and having an axial bore entirely therethrough, saidbore being tapered from opposite ends and decreasing in diameter fromthe ends to the center, and said bit head having a substantiallycylindrical shank portion 2 formed integral therewith, and the taperedbore therein being for reception of the correspondingly tapered end ofthe bit rod 3V.' The a5 lower end of the bit head, opposite to the shankportion, is enlarged on. opposite sides as indicatedv form of depressionwhich will produce this result, 50 whether it be conical, spherical, orotherwise, will suiiice. Obviously the depression, being formed in theend of the bit which is flattened on'opposite sides, results in thelower end of the flattened Y sides being cut away arcuately on an axis'which 55 the cutting face of 26 is at right angles to the bit axis, asis apparent from Figure 1 of the drawings.

Within the tapered bore of the enlarged end of the bit head is installedthe auxiliary cutter portion 5 of the bit, it having a shank which iscorrespondingly tapered and frictionally held' within the bore. Thiscutter portion projects from the bit head within the depression andbeyond the plane of the reaming edges and terminates in opposed straightcutting edges 'I--l formed by plane surfaces intersecting each other atright angles, and leads in the cutting operation. In plan view thiscutter portion 5 of the bit head is illustrated as being of generallyelliptical shape, although this is not essential.

In Figure 5 I have illustrated a plan view of a cross-bit type ofremovable auxiliary portion of bit head and in this instance havingillustrated the same as being composed of four like or similar portions,divided as on the radially disposed lines 8, and it will be obvious thatthe cutting ledges may be installed within the socket in any relation toeach other as for instance they may be all in one plane at right anglesto the axis of the bit or any opposed two of these portions may beinstalled within the socket so that they will lead in the cuttingoperation, while the remaining two portions follow, etc. However, whenthese portions are nested together with their shank portions registeringthey will t within the socket in the outer portion of the bit, as asolid unit. In this connection I wish to call attention to theconvenience in such a compound bit of removal of the auxiliary cuttingportion. For example when the compound bit head is removed from the rod'3, access is readily had through the tapered bore of the outer portionfor driving the auxiliary cutter from its socket either for sharpening,renewal, or adjustment as desired.

It is obvious that such a compound bit asv herein illustrated anddescribed is in no respect confined to the specific form of the cuttingedges here illustrated or to any particular kind of bit, as theadvantages of such a novel compound bit in adapting it to specic kindsof drilling are obvious.

In Figure 6 is illustrated a modifled form of separable bit, theoutermost or major portion of which, indicated at 9, is shown asprovided with the tapered friction socket I0 for reception of thesimilarly tapered terminal II of the bit rod, and which major portion inits drilling e'ect is similar to that shown in Figure 1 of the drawingsin that it forms the reaming portion of the bit, and, in this instance,is provided with an externally tapered axial plug `I2 for reception ofthe auxiliary portion I3, it being provided with a similarly taperedsocket gagement externally of the plug I2, as illus- 'trated. It isobvious, of course, that these tapered frictional connections as hereillustrated, may be the common screw threaded connections, withoutdeparting from the spirit of the invention. And it is also obvious thatwhile I have illustrated the auxiliary portion I3 of the bit as of thechisel type, that a cross, rose, or any'type of bit may be used withequally good results.

In Figure 8 is illustrated a slightly modied form of auxiliary portionof the bit in that it is made of two separable halves divided upon theline I5; this being to illustrate how, if sol desired, the two differenthalves of the auxiliary portion may have unequal angles of thecuttingsedge, as more clearly illustrated in Figure 9. In all of theviews it will be noted that the cutting edge 'of operation that thereaming I4 for frictional en- `needs of this particular the bit isformed by the intersection of plane surfaces at right angles to eachother, but in Figures 8 and 9 it will be noted that `the cutting edge isformed by the intersection of plane surfaces one of which is from theplane of the axis of the bit, and the other 60.therefrom, and this wouldbring the direction of the blow, as far as cutting is concerned, 15 offfrom the vertical. This is quite an advantage so far as wear on the bitis concerned when the functioning of the bit 10 unequal angles, as abovedescribed, it has to be 20 diierent on one side of the center of the bitthan on the other, andtherefore the auxiliary bit is formed in two thecutting edge and facture, simpler to grind, and lending themselvesperfectly to mechanical arrangements of grinding. The two pieces whendriven in the bit will make just as solid a connection as if they wereof one piece, and if it should be desired that one 30 side lead or Workahead of the other side all that is necessary is to drive them in alittle unevenly. 'I'his arrangement of cutting edges is also applicableto the bit shown inlFigure 5.

In Figure 10 is illustrated a bit having two op- 35 posed auxiliarymembers I6 frictionally held within the major. member I1, and it isobvious that there'may be any desired number of such auxiliary membersdepending largely upon the size of the bit being used, and may be ofchisel, 441

cross, rose orany other type and so installed las to lead in the cuttingoperation or follow in respect to the reaming portion of the bit asdesired. In this modication I have shown the reaming edge as beingslightly diierent in form from that of the other embodiments of theinvention.

Thus I have provided a bit wherein consideration is given to the factthat the reaming and the cutting the bits thus far described areprovided with reaming and cutting edges which are separate and distinctfrom one another and therefore adjustable4 in relation to eachother tosuit the need of the particular drilling problem at hand. For in-.` 5.3

stance it may be desired for a particular drilling edges 'of the bitro`- tate in immediate advance when drilling. In Figure 3 it will benoticed that the' two elliptical portions longest diameters at rightangles to each other,- and therefore the cutting edge is exactly midwaybetween the reaming edges as the bit rotated in drilling. Thus, if, asbefore stated, it is desired that the reaming edge advance ofthe cuttingedge, the cutting edge could be loosened and rotated upon its axis, orwithin the socket, anticlockwise about 45, thege/ tightened, and thusprovide .a bit to meet the drilling problem. however, there is aquestion of the eilicient and quick discharge of the material cut, itmay be found that the reaming edge should; follow the cutting edge, inwhich event the cutting edge would be rotated lclockwise in with thevertical. Consequently 15 halves at right angles to along itslongitudinal axis, providing two pieces just alike, simpler to manu- 25vwork performed vby the bit are two separate functions thereof, and, asa consequence,

of the cutting edge of the bit vhave their 80 rotate immediately in d5If, fl

ts socket about 45, and there tightened. It'is thus apparent that thedrilling operator is provided with a bit having heretofore unheard offlexibility, making research possible for any drilling problem, and withthe consequent lessening of the cost thereof.

In Figures 15, 16 and 1'7 is illustrated a type of bit, comprising abody portion 25, attached at one end to a drill rod indicated at 26,saidbit embodying a somewhat modied form to that shown in Figure 6 ofthe drawings, and wherein the axial portion 20 thereof is extendedbeyond the plane of the reaming edges 2l forming the integral centralcutting portion, and the straight cutting edge 22 of which is preferablyonly in length equal to the `distance transverse the opposed corners ofone of the reaming edges 2l, this being particularly convenient insharpening said reaming edges with a hollow conical grinding wheel suchas illustrated at 23.

It is to be noted that'the axially disposed cutter 20 is of straightcylindrical form which is of advantage in maintaining the sturdiestpossible cutting edge of`that portion of the bit,` it being well knownthat where such a chisel shaped bit is formed with the side wallstapered inwardly, the arcuate edges adjacent the-corners of such chiselshaped bit do not support the corners of the cutting edge in an equallyemcient manner and permits of greater grinding areaof the hollowconically shaped grinder for the reaming edges. Y

This integral form of head obviously provides means for modifications inthe discharge of uid to remove the bit cuttings, in that such dischargemay consist of the axial4 hole 24 through the central cutter or it may'consist of a plurality of diagonal openings, such as indicated at 25,bring ing the discharge of the iiuid, whatever it may be, well above thedanger zone of plugging, which, normally occurs under some instances indrilling. i

It is to be noted too that while I have illustrated in all of theaccompanying drawings that form of uniting the separable parts of thebit and Aoperating `rod as employing tapered friction joint connections,it is to be understood that other formsV of connecting said parts may beresorted to without departing from the spirit of the invention.

Furthermore it will be noticed in the several views that the cuttingedge is working deeper in the hole drilled than the reamingedges, andalso that thelength of the cutting edge' is not as long as the diameterof the hole drilled. This increases the speed of cutting since a smallerbit cuts faster than a larger one of the same design, all things beingequal. So that with this arrangement we are cutting a hole of smaller,diameter than desired and then reaming the hole to size with thereaming edges. Thus thereaming edges do more than merely ream the hole,but since the cutting edge isworking in a4 plane lower than the plane ofthe reaming edges, the latter are breaking loose the outside ring notcovered bythe cutting edge, but which gives way easily as soon as thereaming edge starts to penetrate. There is much less work connected 1with reaming this outer part thanl would be required to cut the hole toits full diameter in the first instance.

It is .also conceivable that in certain kinds of material drilled in, itmay be desirable. to havey the reaming edge lead inthe drilling, and, ifso,

the drill 'operator wculd simply remove the cenv ing a cutting edgeextendable entirely across 4from one of the flattened sides to theother.

. intersecting the outer walls of saidenlargement trai cutting portionand replace it with one shorter in axial length so that when installedthe cutting face thereof would not reach to the same plane as that ofthe reaming edge. 1n this type of bit the Ireaming edge is cutting a de-5 pression allA around the perifery of the hole, leaving a central c orewhich is cut by the cutting edge and as a result it breaks up in largerpieces on account of the cut on the perifery which results in fastercutting.` i

It is apparent that in all of the modiiications illustrated, the innerwall ,of the cutting edge of the reaming portion is formed by the walls`of a. conical depression` within the face of the bit, this being trueeven where a. plurality of removable auxiliary bits are employed, as inFigures 10 and 11, such conical depressions being illustrated at I8 inthese figures, the axis of said cones being coincident with the axis ofthe removable bits. This as is obvious providesmost convenient means forresharpening the inside of the cones by the use of a cone shapedgrinder. Having thus described my invention, what I claim and desire tosecure by Letters-Patent, is: 1. A drill bit consisting of -a hollowhead flattened on opposite sides, the outermost lower portions of whichare formed with a pair of cutting edges lying substantially in the samecircle, and al central removable cutting portion hav- 2. A drill bitconsisting of a hollow head fiattened on opposite sides, the outermostportions of which are formed with a pair of arcuate cutting edges lyingin the same circuit, a conical depression intermediate of said cuttingedges, and a cutting portion removably installed within said depressionand having a cutting edge less in length than the distance between saidarcuate cutting edges.

3. A drill bit consisting of a unitary conically concaved head portionflattened upon two opposite sides and the other more remote oppositesides being formed with substantially V-shaped arcuate cutting edgeslying in the same plane, and a removable auxiliary cutting portionmounted within the concavity of said head portion.

4. A drill 'bit consisting of a unitary concaved head portion flattenedupon two opposite sides to providev clearance for the bit cuttings, withthe other more remote opposite sides `being formed with arcuate cuttingedges, said edges being formed by a conical depression in saidconcavity, and a removable auxiliary'cutting portion mounted within saidconical depression.

5. A drill bit consisting of a unitary hollow head portion flattened onvopposite sides and having a conical depression therein forming theoutermost portions oi said head into diametrically opposite arcuatereaming edges lying in the same circle, and a cutter portion -removablyinstalled axially within said conical depression.' .l

6. A drill -bit consisting of a unitary hollow head portion comprising asubstantially cylindrical shank with an enlargement upon two oppositesides adjacent the workingface ofthe bit, a conical depression withinsaid bit, the opposite walls ofsaid depression extending to and l 70 andresulting in a pair of opposite arcuate cut- L ting edges lying in thesame circle and in a plane at right angles to the bit axis and the otheropposite walls of said depression being arcuately cut-away on an axis atright angles to said bit u projecting from said same circle and theopposite attened sides being cut-away to provide clearance for the bitcuttings, and a cutting portion having acutting edge extending in adirection from one flattened side to the other.

8. A drill bit consisting of a relatively short unitary hollow headportion comprising a substantially cylindrical shank portion at one end'with an enlargement upon two opposite sides of the other end, saidenlargements resulting insaid other end being substantially ellipticalin plan view, a conical depression within said other end l, resulting inthe outermost portions thereof being formed with a pair of arcuatecutting edges and the remainder of said other end being cut-away toprovide clearance for the bit cuttings, and a central cutting portionhaving a straight cutting edge extending in a direction from one of theflattened sides to the other.

9. A rock drill bit consisting of a. head portion 4which constitutes theworking end of the bit,

said head portion having a major axis and a minor axis, the major axisbeing the full diameter of the hole to be drilled and the minor axisbeing of lesser diameter, said head portion having a depression insaid'working end forming the working portions of 4said head intodiametrically opposite arcuate reaming edges, the portions of the loweredge of the bit between the arcuate reamin'g edges being cut-away topermit lateral escape of the bit cuttings, and a central cutting portionwithin said depression and having a cutting edge less ein, length thanthe major axis, the walls of said depression being an element of a solidof revolution theaxis of which is coincident with the longitudinal axisof said bit, whereby said arcuate cutting edges may besharpened by a.suitably shaped end grinder revolving about an axis coincident with thelongitudinal axis of the bit.

MARTIN HOKANSON.

